#include <set>
#include <vector>
//
// Created by Administrator on 2025/9/4.
//
int main()
{
    std::vector<int> ivec = {2,4,6,8,2,4,6,8}; // ivec has eight elements
    std::set<int> set2; // empty set
    set2.insert(ivec.cbegin(), ivec.cend()); // set2 has four elements
    set2.insert({1,3,5,7,1,3,5,7}); // set2 now has eight elements
}